Method of making heat treatable coated article with diamond-like carbon (DLC) and/or zirconium in coating

ABSTRACT

In certain example embodiments, a coated article includes respective layers including hydrogenated diamond-like carbon (DLC) and zirconium nitride before heat treatment (HT). During HT, the hydrogenated DLC acts as a fuel which upon combustion with oxygen produces carbon dioxide and/or water. The high temperature developed during this combustion heats the zirconium nitride to a temperature(s) well above the heat treating temperature, thereby causing the zirconium nitride to be transformed into a new post-HT layer including zirconium oxide that is very scratch resistant and durable.

This invention relates to a method of making a coated article to be usedin a window unit or any other suitable application such as furnitureglass or picture frame glass. For example, certain embodiments of thisinvention relate to a method of making a window unit (e.g., vehiclewindow such as vehicle windshield, backlite, sunroof, or sidelite, or IGwindow unit, or shower door) including a step of heat treating a glasssubstrate coated with at least a layer comprising diamond-like carbon(DLC). In certain example embodiments, the DLC may be used to generateenergy during heat treatment (HT) for transforming at least anotherlayer in the coating so as to form a new post-HT layer(s) which was notpresent before the heat treatment. Certain other example embodiments ofthis invention relate to such a coated article, heat treated or not,which may be used in window applications, or any other suitableapplication.

BACKGROUND OF THE INVENTION

Vehicle windows (e.g., windshields, backlites, sunroofs, and sidelites)are known in the art. For purposes of example, vehicle windshieldstypically include a pair of bent glass substrates laminated together viaa polymer interlayer such as polyvinyl butyral (PVB). It is known thatone of the two glass substrates may have a coating (e.g., low-E coating)thereon for solar control purposes such as reflecting IR and/or UVradiation, so that the vehicle interior can be more comfortable incertain weather conditions. Conventional vehicle windshields are made asfollows. First and second flat glass substrates are provided, one ofthem optionally having a low-E coating sputtered thereon. The pair ofglass substrates are washed and booked together (i.e., stacked on oneanother), and then while booked are heat bent together into the desiredwindshield shape at a high temperature(s) (e.g., 8 minutes at about600-625 degrees C.). The two bent glass substrates are then laminatedtogether via the polymer interlayer to form the vehicle windshield.

Insulating glass (IG) window units are also known in the art.Conventional IG window units include at least first and second glasssubstrates (one of which may have a solar control coating on an interiorsurface thereof) that are coupled to one another via at least oneseal(s) or spacer(s). The resulting space or gap between the glasssubstrates may or may not be filled with gas and/or evacuated to a lowpressure in different instances. However, many IG units are required tobe tempered. Thermal tempering of the glass substrates for such IG unitstypically requires heating the glass substrates to temperature(s) of atleast about 600 degrees C. for a sufficient period of time to enablethermal tempering.

Other types of coated articles also require heat treatment (HT) (e.g.,tempering, heat bending, and/or heat strengthening) in certainapplications. For example and without limitation, glass shower doors,glass table tops, and the like require HT in certain instances.

Diamond-like carbon (DLC) is sometimes known for its scratch resistantproperties. For example, different types of DLC are discussed in thefollowing U.S. Pat. Nos. 6,303,226; 6,303,225; 6,261,693; 6,338,901;6,312,808; 6,280,834; 6,284,377; 6,335,086; 5,858,477; 5,635,245;5,888,593; 5,135,808; 5,900,342; and 5,470,661, all of which are herebyincorporated herein by reference.

It would sometimes be desirable to provide a window unit or other glassarticle with a protective coating including DLC in order to protect itfrom scratches and the like. Unfortunately, DLC tends to oxidize andburn off at temperatures of from approximately 380 to 400 degrees C., asthe heat treatment is typically conducted in an atmosphere includingoxygen. Thus, it will be appreciated that DLC as a protective overcoatcannot withstand heat treatments (HT) at the extremely high temperaturesdescribed above which are often required in the manufacture of vehiclewindows, IG window units, glass table tops, and/or the like.Accordingly, DLC cannot be used alone as a coating to be heat treated,because it will oxidize during the heat treatment and substantiallydisappear as a result of the same (i.e., it will burn off).

Certain other types of scratch resistant materials also are not capableof withstanding heat treatment sufficient for tempering, heatstrengthening and/or bending of an underlying glass substrate.

Accordingly, those skilled in the art will appreciate that a need in theart exists for a method of making a scratch resistant coated articlethat is capable of being heat treated (HT) so that after heat treatmentthe coated article is still scratch resistant. A need for correspondingcoated articles, both heat treated and pre-HT, also exists.

BRIEF SUMMARY OF EXAMPLES OF INVENTION

In certain example embodiments of this invention, there is provided amethod of making a coated article (e.g., window unit such as for avehicle, building, or the like) that is capable of being heat treated sothat after being heat treated (HT) the coated article is scratchresistant to an extent more than uncoated glass.

In certain example embodiments, a coated article includes respectivelayers comprising hydrogenated diamond-like carbon (DLC) and zirconiumnitride before heat treatment (HT). During HT, the hydrogenated DLC actsas a fuel which upon combustion with oxygen produces carbon dioxideand/or water. This exothermic reaction, caused by combustion ofhydrogenated carbon of the DLC, causes spontaneous propagation of acombustion wave through the initial reactants. The high temperaturedeveloped during this combustion heats the layer comprising zirconiumnitride to a temperature(s) well above the heat treating temperature,thereby causing the layer comprising zirconium nitride to be transformedinto a new post-HT layer comprising zirconium oxide. The new post-HTlayer comprising zirconium oxide may also include nitrogen in certainexample embodiments of this invention. The new post-HT layer comprisingzirconium oxide is surprisingly scratch resistant. Thus, it can be seenthat a technique has been provided which allows for a heat treatablescratch resistant product; and the coated article may also have goodtransmission properties. In certain example embodiments, the scratchresistance of the post-HT coated article may even be better than that ofnon-HT DLC.

In certain example embodiments, there is provided a method of making aheat treated coated article, the method comprising: providing a coatingsupported by a glass substrate, the coating comprising a layercomprising zirconium nitride and a layer comprising hydrogenateddiamond-like carbon (DLC) provided over at least the layer comprisingzirconium nitride; heat treating the glass substrate and the coating ina manner sufficient for thermal tempering, heat strengthening and/orheat bending the glass substrate; and wherein during said heat treatingthe layer comprising hydrogenated DLC is subject to combustion or burnsoff so as to generate heat sufficient to cause the layer comprisingzirconium nitride to transform into a heat treated layer comprisingzirconium oxide in the heat treated coated article.

In other example embodiments of this invention, there is provided amethod of making a heat treated coated article, the method comprising:providing a coating supported by a glass substrate, the coatingcomprising a layer comprising a metal nitride and a layer comprisingdiamond-like carbon (DLC) provided over at least the layer comprisingthe metal nitride; heat treating the glass substrate and the coating;and wherein, during the heat treating, the layer comprising DLC issubject to combustion or burns off so as to cause the layer comprisingthe metal nitride to transform into a heat treated layer comprising anoxide of the metal in the heat treated coated article. The metal may beZr, or any other suitable metal or metal alloy.

In still further example embodiments of this invention, there isprovided a heat treated coated article including a coating supported bya glass substrate, the coating comprising: an outermost layer comprisingnanocrystalline zirconium oxide comprising cubic lattice structure; andwherein the layer comprising zirconium oxide further comprises from 0.25to 20% carbon.

In other example embodiments of this invention, there is provided acoated article including a coating supported by a glass substrate, thecoating comprising from the glass substrate outwardly: a layercomprising zirconium nitride; and a layer comprising hydrogenateddiamond-like carbon (DLC). Other layers may also be provided in anysuitable location. Such a coated article, in certain exampleembodiments, may be adapted to be heat treated in order to cause thenitride to transform at least partially into an oxide.

In other example embodiments of this invention, there is provided amethod of making a coated article, the method comprising: providing acoating supported by a substrate, the coating comprising a layercomprising diamond-like carbon (DLC) and a layer to be phase-transformedduring heat treatment; heating the layer comprising DLC and the layer tobe phase-transformed in order to cause combustion of the layercomprising DLC thereby causing the layer comprising DLC to generate heatupon combustion thereof; and using the heat generated by combustion ofthe layer comprising DLC to help phase-transform the layer to bephase-transformed so that a new phase-transformed layer is formedfollowing the heating.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram illustrating coated articles according toan embodiment of this invention before and after heat treatment.

FIG. 2 is a schematic diagram illustrating coated articles according toanother embodiment of this invention before and after heat treatment.

FIG. 3 is an XPS graph illustrating chemical elements in a pre-HT coatedarticle according to an example of the instant invention.

FIG. 4 is an XPS graph illustrating chemical elements in the coatedarticle of FIG. 3, after the coated article of FIG. 3 has been subjectedto HT.

FIG. 5 is a schematic diagram illustrating coated articles according toan embodiment of this invention before and after heat treatment.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS OF THE INVENTION

Referring now more particularly to the accompanying drawings in whichlike reference numerals indicate like parts or layers throughout theseveral views.

Certain example embodiments of this invention relate to methods ofmaking coated articles that may use heat treatment (HT), wherein thecoated article includes a coating (one or more layers) includingdiamond-like carbon (DLC) and/or zirconium. In certain instances, the HTmay involve heating a supporting glass substrate, with the DLC and/orzirconium inclusive layer(s) thereon, to temperature(s) of from 550 to800 degrees C., more preferably from 580 to 800 degrees C. (which iswell above the burn-off temperature of DLC). In particular, certainexample embodiments of this invention relate to a technique for allowingthe post-HT coated article to be more scratch resistant than uncoatedglass.

In certain example embodiments, the coated article as originally formed(i.e., prior to HT, or pre-HT) includes respective alternating layerscomprising hydrogenated diamond-like carbon (DLC) and zirconium nitride.During HT (e.g., using temperature(s) of from 550 to 800 degrees C.,more preferably from 580 to 800 degrees C.), the hydrogenated DLC actsas a fuel which upon combustion with oxygen from the atmosphere producescarbon dioxide and water. This exothermic reaction, caused by combustionof the hydrogenated carbon of the DLC, causes spontaneous propagation ofa combustion wave through the initial reactants. The high temperaturedeveloped during this DLC combustion heats the layer(s) comprisingzirconium nitride to a temperature(s) well above the heat treatingtemperature used. For example, the combustion of the DLC may heat partof all of the layer(s) comprising zirconium nitride to a temperature ofat least about 1200 degrees C., more preferably at least about 1500degrees C., and most preferably at least about 2,000 degrees C.

Because the layer(s) comprising zirconium nitride is heated to such ahigh temperature due to the DLC combustion during HT, at least thelayer(s) comprising zirconium nitride is transformed due to the hightemperature(s) into a new post-HT layer(s) comprising zirconium oxide.The new post-HT layer(s) comprising zirconium oxide may also includenitrogen in certain example embodiments of this invention (e.g., ZrO:N;ZrO₂:N, or any other suitable stoichiometry). The new post-HT layer(s)comprising zirconium oxide (optionally with nitrogen) is surprisinglyscratch resistant. Thus, it can be seen that a technique has beenprovided which allows for a heat treatable scratch resistant product tobe made; and the coated article may also have good transmissionproperties. In certain example embodiments, the scratch resistance ofthe post-HT coated article may even be better than that of non-HT DLC.

In certain example embodiments of this invention, the post-HT layer(s)comprising zirconium oxide includes a nanocrystalline cubic latticestructure. The entire layer(s) may be of a nanocrystalline cubic latticestructure type, or alternatively only part of the layer(s) may includenanocrystalline cubic lattice structure. Zirconium nitride typicallydoes not grow in cubic phase unless at a temperature of at least about2,000 degrees C. The ZrN pre-HT is typically not in cubic lattice form.Since the HT is only at a temperature of no greater than about 900degrees C. (more preferably no greater than about 800 degrees C.), onewould expect that the pre-HT non-cubic zirconium nitride would not growin cubic phase during HT. However, it has surprisingly been found thatthe combustion generated by the DLC during HT causes at least part ofthe layer comprising zirconium nitride to be heated sufficiently tocause it to transform into a post-HT layer(s) comprising zirconium oxidewhich includes a nanocrystalline cubic lattice structure (with orwithout nitrogen) which is very scratch resistant.

Thus, it can be seen that in certain example embodiments of thisinvention the pre-HT zirconium nitride inclusive layer is transformedduring HT into a new post-HT layer comprising zirconium oxide includinga nanocrystalline cubic lattice structure, even though the temperaturesused by the furnace during HT are well less than those required fortypically allowing the cubic growth. It is the combustion of the DLCduring HT which causes enough energy/heat to be generated at thezirconium inclusive layer in order to allow it to change phase and growin at least a cubic manner so as to finally comprise a nanocrystallinecubic lattice structure following HT.

As a result of the HT, the amount of oxygen in the post-HT zirconiuminclusive layer(s) is much higher than the amount of oxygen in thepre-HT zirconium inclusive layer(s). For example, in certain exampleembodiments of this invention, the post-HT layer(s) comprising zirconiumoxide includes at least 5 times as much oxygen as the pre-HT layer(s)comprising zirconium nitride, more preferably at least 10 times as much,and most preferably at least 20 times as much oxygen as the pre-HTlayer(s). In certain example embodiments of this invention, the pre-HTlayer(s) comprising zirconium nitride includes from about 0-10% oxygen,more preferably from about 0-5% oxygen, and most preferably from about0-2% (atomic %) oxygen. Meanwhile, in certain example embodiments ofthis invention, following HT and phase transformation due to DLCcombustion, the post-HT layer(s) comprising zirconium oxide includesmuch more oxygen as will be explained below.

FIG. 1 is a schematic diagram illustrating how a coated article can bemade according to an example embodiment of this invention. Initially, acoated article is formed using a glass substrate 1. The coated articleincludes, supported by glass substrate 1, at least one optionaldielectric layer 3 of or including silicon nitride, silicon oxynitride,silicon oxide, or the like; a first layer of or including DLC 5, a firstlayer of or including zirconium nitride 7 (e.g., ZrN, or any othersuitable stoichiometry), and a top layer of or including DLC 9. Glasssubstrate 1 is typically of or includes soda-lime-silica glass, althoughother types of glass may be used in certain instances.

Dielectric layer(s) 3 is provided in order to prevent sodium diffusioninto the DLC during HT (i.e., a diffusion barrier). This layer(s) 3 alsopermits thermal mismatching to occur without problems between the DLCand the glass substrate so as to more easily permit heat bending and thelike. Unexpectedly, it has been found that the use of silicon oxide as abarrier layer 3 (compared to silicon nitride) often leads to improvedoptical results of the final product after heat treatment such as highervisible transmission. Any of the aforesaid barrier layer 3 materials maybe doped (e.g., 0.5 to 15%) with Al, stainless steel, or any othermetal(s) in certain embodiments of this invention. Barrier layer(s) 3 isformed on the glass substrate 1 via sputtering, or via any othersuitable technique.

The layers 5 and 9 comprising DLC may be of any suitable type of DLC,including but not limited to any of the DLC types described in any ofU.S. Pat. Nos. 6,592,993; 6,592,992; 6,531,182; 6,461,731; 6,447,891;6,303,226; 6,303,225; 6,261,693; 6,338,901; 6,312,808; 6,280,834;6,284,377; 6,335,086; 5,858,477; 5,635,245; 5,888,593; 5,135,808;5,900,342; and/or 5,470,661, all of which are hereby incorporated hereinby reference.

For purposes of example only, DLC inclusive layer(s) 5 and/or 9 may eachbe from about 5 to 1,000 angstroms (Å) thick in certain exampleembodiments of this invention, more preferably from 10-300 Å thick, andmost preferably from 45 to 65 Å thick. In certain example embodiments ofthis invention, DLC layer(s) 5 and/or 9 may have an average hardness ofat least about 10 GPa, more preferably at least about 20 GPa, and mostpreferably from about 20-90 GPa. Such hardness renders layers 5 and 9resistant to scratching, certain solvents, and/or the like. Layer(s) 5and/or 9 may, in certain example embodiments, be of or include a specialtype of DLC known as highly tetrahedral amorphous carbon (t-aC), and maybe hydrogenated (t-aC:H) in certain embodiments. In certain hydrogenatedembodiments, the t-aC:H type of DLC may include from 4 to 39% hydrogen,more preferably from 5-30% H, and most preferably from 10-20% H.

This t-aC or t-aC:H type of DLC for layer(s) 5 and/or 9 may include moresp³ carbon-carbon (C—C) bonds than sp² carbon-carbon (C—C) bonds. Incertain example embodiments, at least about 50% of the carbon-carbonbonds in DLC layer(s) 5 and/or 9 may be sp³ type carbon-carbon (C—C)bonds, more preferably at least about 60% of the carbon-carbon bonds inthe layer(s) may be sp³ carbon-carbon (C—C) bonds, and most preferablyat least about 70% of the carbon-carbon bonds in the layer(s) may be sp³carbon-carbon (C—C) bonds. In certain example embodiments of thisinvention, the DLC in layer(s) 5 and/or 9 may have an average density ofat least about 2.4 gm/cm³, more preferably at least about 2.7 gm/cm³.

Example linear ion beam sources that may be used to deposit DLCinclusive layers 5 and 9 on substrate 1 include any of those in any ofU.S. Pat. Nos. 6,261,693, 6,002,208, 6,335,086, or 6,303,225 (allincorporated herein by reference). When using an ion beam source todeposit layer(s) 5 and/or 9, hydrocarbon feedstock gas(es) (e.g., C₂H₂),HMDSO, or any other suitable gas, may be used in the ion beam source inorder to cause the source to emit an ion beam toward substrate 1 forforming layer(s) 5 and/or 9. It is noted that the hardness and/ordensity of layer(s) 5 and/or 9 may be adjusted by varying the ion energyof the depositing apparatus. It is noted that the phrase “on thesubstrate” as used herein is not limited to being in direct contact withthe substrate as other layer(s) may still be provided therebetween.

Zirconium nitride inclusive layer 7 is provided between DLC layers 5 and9 in certain example embodiments of this invention. In certain exampleembodiments, zirconium nitride inclusive layer 7 may be located directlybetween DLC layers 5 and 9 so as to contact each of them; however inother example embodiments other layer(s) (not shown) may be providedbetween the zirconium nitride inclusive layer 7 and the DLC layer(s) 5and/or 9. The zirconium nitride inclusive layer 7 may consistessentially of zirconium and nitride, or alternatively may include othermaterials including but not limited to oxygen, or other dopants such asAl or the like. Zirconium nitride inclusive layer 7 may be formed bysputtering or the like in certain example embodiments of this invention.The pre-HT layer(s) comprising zirconium nitride 7 (and 7′ discussedbelow) may include from about 10-70% Zr, more preferably from about30-65% Zr, even more preferably from about 40-60% Zr, and mostpreferably from about 45-55% Zr in terms of atomic %; and from about20-60% N, more preferably from about 30-50% N in terms of atomic %.

In certain example embodiments of this invention, zirconium nitrideinclusive layer 7 (and 7′ to be discussed below) may have a density ofat least 6 gm/cm³, more preferably at least 7 gm/cm³. Additionally, incertain example embodiments, zirconium nitride layer 7 (and 7′) may havean average hardness of at least 650 kgf/mm, more preferably of at least700 kgf/mm, and/or may have a bond overlap population of at least 0.25(more preferably at least about 0.30) for strength purposes. In certainexample instances, many of the Zr—N bonds in layer 7 (and 7′) may be ofthe covalent type, which are stronger than ionic bonds, for strengthpurposes. It is also noted that in certain example embodiments of thisinvention, the ZrN of layer 7 (and 7′) may have a melting point of atleast 2,500 degrees C., and it may be about 2,980 degrees C. in certainexample instances. In certain example embodiments of this invention, thezirconium nitride of layer 7 (and 7′) may be represented by Zr_(x)N_(y),where the ratio x:y is from 0.8 to 1.2, and is preferably about 1.0 incertain example embodiments.

For purposes of example only, certain example thicknesses for the pre-HTlayers shown on the left side of FIG. 1 are set forth below, with thelayers being listed in order from the glass substrate outwardly.

Example Coating (FIG. 1) - Layer Thicknesses (Pre-HT) Layer General MorePreferred Most Preferred Dielectric (layer 3) 50-500 Å 100-300 Å 180-220 Å DLC (layer 5) 10-300 Å 15-100 Å  20-45 Å ZrN (layer 7) 40-500Å 50-400 Å  90-220 Å DLC (layer 9) 20-300 Å 30-100 Å  40-65 Å

Once the pre-HT coated article shown on the left side of FIG. 1 isformed, it may or may not be subjected to heat treatment sufficient forat least one of heat bending, thermal bending, and/or heatstrengthening.

Referring to FIG. 1, when subjected to HT (e.g., in a furnace usingtemperature(s) of from 550 to 800 degrees C., more preferably from 580to 800 degrees C.), the upper or outer DLC inclusive layer 9 burns offdue to combustion because of the high temperatures used during HT. Inparticular, at least hydrogenated DLC layer 9 acts as a fuel which uponcombustion with oxygen from the atmosphere during HT produces carbondioxide and water. This exothermic reaction, caused by combustion ofhydrogenated carbon from at least DLC layer 9, causes spontaneouspropagation of a combustion wave through the initial reactants. The hightemperature developed during this combustion heats the layer 7comprising zirconium nitride to a temperature(s) well above the heattreating temperature used by the furnace. For example, the combustion ofthe DLC 9 may heat part of all of the layer 7 comprising zirconiumnitride to a temperature of at least about 1200 degrees C., morepreferably at least about 1500 degrees C., and most preferably at leastabout 2,000 degrees C.

Because the layer comprising zirconium nitride 7 is heated to such ahigh temperature due to the DLC combustion during HT, the layercomprising zirconium nitride 7 is transformed during the HT into a newpost-HT layer comprising zirconium oxide 11. The new post-HT layercomprising zirconium oxide 11 may also include nitrogen (and/or otherdopants) in certain example embodiments of this invention (e.g., ZrO:N;ZrO₂:N; or any other suitable stoichiometry). The new post-HT layercomprising zirconium oxide 11 (optionally with nitrogen) is surprisinglyscratch resistant thereby providing a heat treated scratch resistantcoated article. It is noted that the phrase “zirconium oxide” as usedherein includes ZrO₂ and/or any other stoichiometry where Zr is at leastpartially oxided. Herein, any description of layer 11 also may apply tolayer 11′; and likewise any description of layer 7 may apply to layer7′.

The post-HT layer comprising zirconium oxide 11 may include from 0-30%nitrogen in certain example embodiments of this invention, morepreferably from 0-20% nitrogen, even more preferably from 0-10%nitrogen, and most preferably from about 1-5% nitrogen in certainexample embodiments of this invention. The post-HT layer comprisingzirconium oxide 11 may include from about 10-70% Zr, more preferablyfrom about 20-60% Zr, even more preferably from about 30-55% Zr, andmost preferably from about 30-45% Zr in terms of atomic %. Moreover, thepost-HT layer(s) comprising zirconium oxide 11 in certain exampleembodiments of this invention may include from about 10-85% oxygen, morepreferably from about 30-80% oxygen, even more preferably from about40-70% oxygen, and most preferably from about 50 to 70% oxygen.

In certain example embodiments of this invention, the post-HT layercomprising zirconium oxide 11 includes a nanocrystalline cubic latticestructure (although the pre-HT layer comprising zirconium nitride didnot in certain instances). As explained above, zirconium nitridetypically does not grow in cubic phase unless at a temperature of atleast about 2,000 degrees C. It has surprisingly been found that thecombustion generated by the DLC during HT causes at least part of thepre-HT layer comprising zirconium nitride 7 to be heated sufficiently tocause it to grow in the cubic phase and become a post-HT layer 11comprising a nanocrystalline cubic lattice structure including zirconiumoxide (with or without nitrogen) which is very scratch resistant incertain example embodiments of this invention.

It has surprisingly been found that the use of zirconium nitride (e.g.,ZrN) in the pre-HT layer 7 is especially beneficial with respect toallowing a post-HT phase-transformed layer 11 including Zr to be formedwhich is very scratch resistant.

The final HT (or even the non-HT) coated article of FIG. 1 is scratchresistant and may be used in various applications, including but notlimited to IG window units, laminated vehicle windshields, other typesof vehicle windows, furniture applications, and/or the like.

For purposes of example only, certain example thicknesses for thepost-HT coated article shown on the right side of FIG. 1 are set forthbelow, with the layers being listed in order from the glass substrateoutwardly.

Example Coating (FIG. 1) - Layer Thicknesses (Post-HT) Layer GeneralMore Preferred Most Preferred Dielectric (layer 3) 50-500 Å 100-300 Å 180-220 Å DLC (layer 5) 10-300 Å 15-100 Å  20-45 Å ZrO:N (layer 11)50-800 Å 70-600 Å 100-350 Å

It can be seen from the above that post-HT Zr inclusive layer 11 istypically thicker than is pre-HT Zr inclusive layer 7. In other words,the thickness of the Zr inclusive layer increases during HT. In certainexample embodiments of this invention, the thickness of the Zr inclusivelayer (e.g., from layer 7 to layer 11) may increase at least about 5%during or due to HT, more preferably at least about 10%, and mostpreferably at least about 40%. This increase in thickness is caused bythe transformation of layer 7 into layer 11, where oxygen migrates intothe post-HT layer 11 (i.e., more oxygen migrates into the post-HT layer11 than nitrogen leaves in terms of atomic % and/or size).

While the DLC layer 5 is shown as being present in the post-HT coatedarticle in FIG. 1, it need not be present in the post-HT coated articlein alternative embodiments of this invention. If the pre-HT DLC layer 5reaches sufficient temperature and/or is exposed to enough oxygen duringHT, it may be subject to combustion thereby causing it to decrease inthickness or even vanish due to HT in certain instances. In such cases,the pre-HT layers 5, 7 and 9 may be effectively transformed during HTinto post-HT zirconium oxide inclusive layer 11 (it is similar to theFIG. 5 embodiment in this regard).

In certain example embodiments of this invention, the heat treated layer11 comprising zirconium oxide includes Zr_(x)O_(y) wherein y/x is fromabout 1.2 to 2.5, more preferably from about 1.4 to 2.1.

FIG. 2 illustrates another example embodiment according to thisinvention. The FIG. 2 embodiment is similar to the FIG. 1 embodiment,except that additional ZrN inclusive layer(s) 7′ and additional DLCinclusive layer(s) 5′ are provided pre-HT. In other words, the FIG. 2embodiment includes plural sets of alternating layers comprising DLC andZrN pre-HT. Thus, following HT, an additional zirconium oxide inclusivelayer(s) 11′ and an additional DLC inclusive layer 5′ may be provided asshown on the right side of FIG. 2. Layers 5′, 7′, and 11′ are similar tolayers 5, 7, and 11, respectively, discussed above, in certain exampleembodiments of this invention. However, it is possible that one or bothof hydrogenated DLC layers 5, 5′ may be subject to combustion andsubstantially disappear or substantially decrease in thickness due to HTin certain example embodiments of this invention when high temperatureand/or long heating times are used so that a single ZrO layer remains(e.g., see FIG. 5), although some DLC may remain as shown in FIG. 2.However, as shown in the FIG. 2 embodiment, at least the outerhydrogenated DLC layer 9 typically burns off due to combustion andgenerates the energy/heat needed to cause one of more of the ZrNlayer(s) 7, 7′ to transform into ZrO inclusive layer(s) 11, 11′ asexplained above.

Still referring to the FIG. 2 embodiment, in certain examplenon-limiting embodiments of this invention, oxygen from the atmospherediffuses inwardly through the layers(s) in order to help the pre-HTzirconium nitride layers 7 and 7′ to transform, aided by the heatgenerated by the combustion discussed above, into the post-HT layers 11and 11′ comprising zirconium oxide. However, in other exampleembodiments of this invention, pre-HT zirconium nitride layer 7′ neednot phase transform during HT; in such embodiments, the post-HT layer11′ would be similar to the pre-HT layer 7′ and consist essentially ofzirconium nitride. In still other embodiments of this invention, layer11′ may be partially transformed and thus include a mixture of zirconiumnitride and zirconium oxide.

FIGS. 3-5 illustrate another example embodiment of this invention. Thepre-HT coated article of this embodiment is the same as that of the FIG.2 embodiment described above. FIG. 3 is an XPS graph illustrating thechemical make-up of an example coated article pre-HT according to theFIG. 5 embodiment. However, in contrast to the FIG. 2 illustratedembodiment, in the FIG. 5 embodiment during HT all DLC layers aresubject to combustion and essentially disappear. This in turn creates asignificant amount of heat and coupled with oxygen diffusing into thecoating from the surrounding atmosphere causes each of the pre-HTzirconium nitride layers to phase transform during HT so as to form atleast one post-HT layer comprising zirconium oxide (which may or may notbe doped with N) 11. In the FIG. 5 embodiment, the pre-HT layers 5, 7′,5′, 7 and 9 merge into or ultimately result in one rather thick post-HTlayer comprising zirconium oxide 11. FIG. 4 is an XPS graph illustratingthe chemical make-up of an example post-HT coated article according tothe FIG. 5 embodiment.

In the FIG. 3-5 embodiment, it can be seen in FIG. 4 that residualcarbon remains in the zirconium oxide layer 11 following HT due to thepresence of the pre-HT DLC layer(s). In certain example embodiments ofthis invention, the zirconium oxide layer 11 includes from 0.25 to 20%C, more preferably from 0.25 to 10% C, and most preferably from 0.25 to5% C.

Each of the aforesaid embodiments provides for a heat treatable coatedarticle that is very scratch resistant following HT. For example,post-HT coated articles according to certain embodiments of thisinvention may have a critical scratch load using an alumina sphere of atleast about 15 lbs., more preferably at least 18 lbs., even morepreferably at least 20 lbs., still most preferably at least 22.5 lbs.,and most preferably at least 30 lbs. Additionally, coated articlesaccording to certain example embodiments of this invention are UVstable, and do not significantly degrade upon UV exposure. In certainexample embodiments, coated articles herein may have a post-HT contactangle θ with a sessile drop of water of from about 25 to 60 degrees; andsometimes the contact angle is less than 35 degrees.

Moreover, in certain example embodiments, good optics are provided inthat no significant yellow tint is present post-HT even though yellowishDLC may have been present at least in the pre-HT version of the product.The resulting heat treated coated article is surprisingly transmissiveto visible light. For example, the heat treated coated article may havea visible transmission of at least 50%, more preferably of at least 60%,even more preferably of at least 70%, more preferably at least 75%, andsometimes at least 80% according to certain example embodiments of thisinvention. According to certain example embodiments of this invention,post-HT coated articles have a transmissive a* value of from −5 to +2,more preferably from −4 to 0, and most preferably from −3.5 to −1; and atransmissive b* value of from −8 to +8, more preferably from −3 to +3,and most preferably from −2 to +2. In other words, heat treated coatedarticles according to certain example embodiments of this inventionvisually appear very similar to clear uncoated glass, even though thenumerous layers for durability purposes are provided thereon.

Another unique aspect of certain example embodiments of this inventionis the extreme increase in visible transmission caused by heattreatment. In certain example embodiments, visible transmissionincreases by at least about 20 visible transmission % due to HT, morepreferably at least 30%, and most preferably at least 40%. For example,in certain examples of this invention that have been made, the pre-HTvisible transmission has been about 36-37%. Following heat treatment forabout 400 seconds at about 640 degrees C., the post-HT visibletransmission was about 77-81%. In each case, the visible transmissionincreased by about 40-45% due to HT. For purposes of example andunderstanding, if a pre-HIT coated article had a visible transmission of36% and following HT the post-HT coated article had a visibletransmission of 80%, then the visible transmission increased 44% (i.e.,80%-36%=44%) due to HT. The apparent reason for this significantincrease in visible transmission due to HT is the vanishing of at leastsome DLC due to HT because of the aforesaid combustion thereof. DLCblocks visible transmission to some extent, and its combustion anddisappearance during HT allows visible transmission of the resulting HTcoated article to significantly increase as shown above. Thus, not onlydoes the DLC combustion act as a fuel which allows transformation of theZr inclusive layer, but it also allows visible transmission tosignificantly increase.

Any suitable type of glass substrate 1 may be used in differentembodiments of this invention. For example, various types of soda limesilica glass or borosilicate glass may be used for substrate 1. However,in certain example embodiments of this invention, the coating of any ofthe aforesaid embodiments may be supported by a special type of glasssubstrate that has a very high visible transmission and a very clearcolor. In particular, in such certain example embodiments of thisinvention, the glass substrate 1 may be any of the glasses described incommonly owned U.S. patent application Ser. No. 10/667,975, thedisclosure of which is hereby incorporated herein by reference. Incertain preferred embodiments, the resulting glass has visibletransmission of at least 85%, more preferably at least 88%, and mostpreferably at least 90% (e.g., at a reference thickness of about 0.219inches or 5.56 mm). The advantage of using such a glass substrate 1 isthat the resulting HT product is caused to have a visual appearancesimilar to that of uncoated clear glass—even though the coating isprovided thereon. In addition to the base glass, examples of the glassbatch and/or final glass are set forth below (in terms of weightpercentage of the total glass composition, unless otherwise listed asppm):

Example Colorants and Oxidizer Cerium in Glass Substrate IngredientGeneral Preferred More Preferred Best total iron (Fe₂O₃):  0.01-0.20% 0.01-0.15%  0.02-0.12% 0.04 to 0.10% cobalt oxide: 0.1 to 15 ppm 0.3 to10 ppm 0.5 to 5 ppm  0.5 to 3 ppm cerium oxide:  0.005-1.0%  0.01-1.0% 0.01-0.5% 0.05 to 0.2% titanium oxide:   0 to 0.5%   0 to 0.2% 0.001 to0.05% 0.01 to 0.02% chromium oxide:   0 to 10 ppm   0 to 8 ppm   0 to 5ppm   1 to 5 ppm glass redox: <=0.12 <=0.10 <=0.08 <=0.05 % FeO:0.0001-0.05% 0.0001-0.01% 0.001-0.008% 0.001-0.003%

It is noted that in other embodiments of this invention, additionallayers (not shown) may be added to the coated articles discussed above,and/or certain layer(s) may be deleted.

EXAMPLE

For purposes of example, and without limitation, the following examplecoated article was made and tested according to an example embodiment ofthis invention. This Example is similar to the FIG. 5 embodiment.

The glass substrate 1 was cleaned/washed. It was then ion beam etchedusing argon gas to clean the surface thereof. Then, a silicon nitridebarrier layer 3 (doped with Al) about 100 Å thick, a DLC (ta-C:H type)layer 5 about 70 Å thick, a zirconium nitride layer 7′ about 100 Åthick, another DLC (ta-C:H type) layer 5′ about 70 Å thick, anotherzirconium nitride layer 7 about 100 Å thick, and a sacrificial outer DLC(ta-C:H type) layer 9 about 70 Å thick were formed on a glass substrate(see FIG. 5). The ZrN layers 7 and 7′ were formed via sputtering a Zrtarget in an atmosphere including N and Ar, and the DLC layers wereformed via ion-beam deposition using an anode-cathode voltage of about3,000 V and acetylene feedstock gas.

FIG. 3 is an XPS graph illustrating the pre-HT chemical make-up of thecoated article according to this Example. As can be seen in FIG. 3, thecarbon (C) spikes indicate the DLC layers 5 and 5′, whereas the Zrspikes indicate the ZrN layers 7 and 7′. It is noted that the C contentincreases on the left edge of the FIG. 3 graph showing the thin DLCsacrificial layer 9 at the outermost layer of the pre-HT coating. Thehigh oxygen content on the right side of the graph indicates the glasssubstrate, and the combination of the Si and N spikes in the same areaindicates the optional silicon nitride barrier layer 3.

The coated article in the Example was then subjected to HT at about 625degrees C. for about four minutes.

FIG. 4 is an XPS graph of the coated article of FIG. 3 (i.e., of thisExample) after the HT. FIG. 4 illustrates that the overcoat DLC layer 9burned off during HT due to combustion, and that pre-HT layers 5, 7′, 5′and 7 merged or were transformed into a thick layer consistingessentially of scratch resistant zirconium oxide 11 that was slightlydoped with nitrogen (see the right-hand coated article in FIG. 5 whichis the post-HT article). It can be seen in FIG. 4 that residual carbonis left over in the zirconium oxide layer 11 due to the previous DLClayers which were present prior to heat treatment.

While the invention has been described in connection with what ispresently considered to be the most practical and preferred embodiments,it is to be understood that the invention is not to be limited to thedisclosed embodiments, but on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims.

1. A method of making a heat treated coated article, the methodcomprising: having a coating supported by a glass substrate, the coatingcomprising a layer comprising zirconium nitride and a layer comprisinghydrogenated diamond-like carbon (DLC) provided over at least the layercomprising zirconium nitride; heat treating the glass substrate and thecoating in a manner sufficient for thermal tempering, heat strengtheningand/or heat bending the glass substrate; and wherein during said heattreating the layer comprising hydrogenated DLC is subject to combustionor burns off so as to generate heat sufficient to cause the layercomprising zirconium nitride to transform into a heat treated layercomprising zirconium oxide in the heat treated coated article.
 2. Themethod of claim 1, wherein the heat treated layer comprising zirconiumoxide comprises a nanocrystalline cubic lattice structure.
 3. The methodof claim 1, wherein the heat treated layer comprising zirconium oxidecomprises from about 30-80% oxygen.
 4. The method of claim 1, whereinthe heat treated layer comprising zirconium oxide comprises from about50 to 70% oxygen.
 5. The method of claim 1, wherein the heat treatedlayer comprising zirconium oxide comprises from about 20-60% Zr.
 6. Themethod of claim 1, wherein the heat treated layer comprising zirconiumoxide comprises from about 30-55% Zr.
 7. The method of claim 1, whereinthe heat treated layer comprising zirconium oxide comprises from about30-45% Zr and from about 0-10% N.
 8. The method of claim 1, wherein theheat treated layer comprising zirconium oxide includes Zr_(x)O_(y),wherein y/x is from about 1.2 to 2.5.
 9. The method of claim 1, whereinthe heat treated layer comprising zirconium oxide includes Zr_(x)O_(y),wherein y/x is from about 1.4 to 2.1.
 10. The method of claim 1, whereinduring the heat treating the layer comprising zirconium nitride isheated to a temperature higher than a temperature used by a heattreating furnace due to combustion of the layer comprising DLC, so as toallow the heat treated layer comprising zirconium oxide to grow at leastpartially in cubic form.
 11. The method of claim 1, wherein the coatedarticle prior to the heat treating comprises and additional layercomprising DLC and an additional layer comprising zirconium nitride. 12.The method of claim 1, wherein the heat treated coated article includesat least one dielectric layer and/or at least one layer comprising DLClocated between the glass substrate and the layer comprising zirconiumoxide.
 13. The method of claim 12, wherein the dielectric layercomprises silicon oxide and/or silicon nitride.
 14. The method of claim1, wherein the heat treated layer comprising zirconium oxide consistsessentially of zirconium oxide.
 15. The method of claim 1, wherein theheat treated coated article is scratch resistant and has a criticalscratch load using an alumina sphere of at least about 20 lbs.
 16. Themethod of claim 1, wherein the layer comprising zirconium oxide is anoutermost layer of the heat treated coated article.
 17. The method ofclaim 1, wherein visible transmission % of the coated article increasesby at least 30% due to the heat treating.
 18. The method of claim 1,wherein visible transmission % of the coated article increases by atleast 40% due to the heat treating.
 19. The method of claim 1, whereinthe heat treated coated article comprises, from the glass substrateoutwardly, the following successive layers: a dielectric layer, a layercomprising DLC, and the layer comprising zirconium oxide.
 20. The methodof claim 1, wherein the heat treated coated article has a transmissivea* value of from −4 to 0, and a transmissive b* value of from −3 to +3.21. The method of claim 1, wherein the heat treated coated article has avisible transmission of at least 60%.
 22. The method of claim 1, whereinthe heat treated coated article has a visible transmission of at least75%.
 23. The method of claim 1, wherein the heat treated layercomprising zirconium oxide is at least 10% thicker than the layercomprising zirconium nitride which was not heat treated.
 24. The methodof claim 1, wherein the heat treated layer comprising zirconium oxide isat least 40% thicker than the layer comprising zirconium nitride whichwas not heat treated.
 25. The method of claim 1, wherein the layercomprising DLC includes from 5 to 30% hydrogen.
 26. The method of claim1, wherein the layer comprising DLC comprises sp³ carbon-carbon (C—C)bonds and has an average density of at least about 2.4 gm/cm³.
 27. Themethod of claim 1, wherein the layer comprising DLC is not present inthe heat treated coated article, as it burned off during said heattreating.
 28. The method of claim 1, wherein the layer comprising DLCwas the outermost layer of the coated article before the heat treating.29. The method of claim 1, wherein the glass substrate includes a baseglass portion comprising: SiO₂ at least 67% Na₂O 10 to 20% CaO  5 to 15%MgO 0 to 8% Al₂O₃ 0 to 5% K₂O 0 to 5%

and a colorant portion comprising: total iron (expressed Fe₂O₃):  0.01to 0.20% cobalt oxide:   0.1 to 15 ppm chromium oxide:    0 to 10 ppmtitanium oxide:    0 to 0.5% glass redox: <=0.10 % FeO: 0.0001 to 0.05%

and wherein the glass substrate with no coating thereon has a visibletransmission of at least about 85%.
 30. A method of making a heattreated coated article, the method comprising: having a coatingsupported by a glass substrate, the coating comprising a layercomprising a metal nitride and a layer comprising diamond-like carbon(DLC) provided over at least the layer comprising the metal nitride;heat treating the glass substrate and the coating; and wherein, duringthe heat treating, the layer comprising DLC is subject to combustion orburns off so as to cause the layer comprising the metal nitride totransform into a heat treated layer comprising an oxide of the metal inthe heat treated coated article.
 31. The method of claim 30, wherein theheat treated layer comprises a nanocrystalline cubic lattice structure,and wherein the layer comprising the metal nitride did not include acubic lattice structure prior to the heat treating.
 32. The method ofclaim 30, wherein the metal comprises Zr.
 33. A method of making acoated article, the method comprising: having a coating supported by asubstrate, the coating comprising a layer comprising diamond-like carbon(DLC) and a layer comprising metal nitride to be phase-transformedduring heat treatment; heating the layer comprising DLC and the layercomprising metal nitride to be phase-transformed in order to causecombustion of the layer comprising DLC thereby causing the layercomprising DLC to generate heat upon combustion thereof; and using heatgenerated by combustion of the layer comprising DLC to helpphase-transform the layer to be phase-transformed so that a newphase-transformed layer is formed.
 34. The method of claim 33, whereinthe layer to be phase-transformed and the new phase-transformed layereach comprise Zr.
 35. The method of claim 33, whereinphase-transformation of the layer to be phase-transformed comprises eachone of: (a) changing from a nitride based layer to an oxide based layer;and (b) changing a molecular, bonding, and/or crystallinity structure ofat least part of the layer.
 36. The method of claim 33, wherein duringthe heating the layer to be phase-transformed is heated to a temperaturehigher than a temperature used by a heat treating furnace due tocombustion of the layer comprising DLC, so as to allow the newphase-transformed layer to grow at least partially in cubic and/orcrystalline form, and wherein the new phase-transformed layer comprisesmetal oxide.
 37. The method of claim 33, wherein the layer comprisingDLC comprises from 5 to 30% hydrogen.
 38. A method of making a coatedarticle, the method comprising: providing a coating supported by a glasssubstrate, the coating comprising a combustible layer comprisingdiamond-like carbon, and a layer comprising metal nitride to bephase-transformed during heat treatment; heating the combustible layerand the layer comprising metal nitride to be phase-transformed in orderto cause combustion of the combustible layer thereby causing thecombustible layer to generate heat upon combustion thereof; using heatgenerated by combustion of the combustible layer to help phase-transformthe layer comprising metal nitride, so that a new phase-transformedlayer is formed; and wherein the new phase-transformed layer comprisesat least one of (i) zirconium oxide, and (ii) a cubic lattice structure.39. The method of claim 38, wherein the combustible layer compriseshydrogenated diamond-like carbon (DLC).